Aleurone tissue from undried immature developing wheat grains (Triticum aestivum L. cv. Sappo), normally insensitive to gibberellic acid, can be made to respond to the hormone by a series of temperature treatments. Incubation of the de-embryoed grains at temperatures above 27° C for at least 8 h causes the tissue to become sensitive. Prolonged incubation at temperatures below 27° C does not effect a change in sensitivity. In addition to the requirement for exposure to an elevated temperature for a period of several hours the tissue must also subsequently be subjected to a period at a lower temperature for just a few seconds for the response to be observed. Once sensitized, the tissue remains responsive to gibberellic acid for substantial periods of time. Exposure of the tissue to temperatures which induce sensitivity to gibberellic acid also results in an increased leakage of amino acids. It is suggested that the increase in sensitivity to gibberellin requires two separate processes to take place. One could be a homeoviscous adaptation of the cell membranes in response to elevated temperature, the other a subsequent, permanent change in conformation of membrane components.

The induction of sensitivity to gibberellin in aleurone tissue of developing wheat grains : II. Evidence for temperature-dependent membrane transitions.

Metabolism of [14C]- and [36Cl]-labeled vinyl chloride in vivo and in vitro

Aleurone layers from immature developing wheat grains (Triticum aestivum L. cvs. Sappo. and Champlein), though normally insensitive, can be made to produce α-amylase in response to gibberellic acid by subjecting the grains to a period of enforced dehydration prior to introduction to the hormone. The change in sensitivity appears to depend upon the water content of the tissue, water levels of below approximately 25% being critical for the effect. Grain detachment or duration of drying apparently do not qualitatively influence the development of sensitivity to gibberellic acid. Enhanced sensitivity resulting from drying is not caused by changes in gibberellic acid uptake. A possible mechanism for the change in sensitivity of aleurone cells might be through structural alterations in cell membranes.

The induction of sensitivity to gibberellin in aleurone tissue of developing wheat grains : I. The effect of dehydration.

The hydrogen bond structure of a series of poly(methacrylic acid) (PMAA) complexes was studied by solid-state NMR. 13C and 2H labeled PMAA samples were complexed with poly(ethylene oxide) (PEO), poly(vinyl methyl ether) (PVME), poly(acrylamide) (PAAM), poly(vinyl caprolactam) (PVCL) and poly(vinylpyrrolidone) (PVPon). The presence and relative strengths of PMAA’s hydrogen bonds with itself versus those with the complementary polymer was assessed by combining 13C CP-MAS NMR, 1H–13C HETCOR, 1D and 2D DQ 1H MAS NMR experiments. Analyses of 1H DQ spinning sideband patterns gave estimates of the proton–proton distances. Only the polyether–PMAA complexes, PEO and PVME, show resolved 13C and 1H resonances. This spectral resolution is proposed to be due to the selective disruption and stabilization of PMAA’s open and cyclic dimers, respectively. Residual PMAA dimers are detected by 1H NMR for the polylactam complexes, PVCL and PVPon, but both types dimers are weakened, reflecting the greater amount of interpolyme...

1H Solid State NMR Study of Poly(methacrylic acid) Hydrogen-Bonded Complexes

The chain mobility of a series of hydrogen-bonded polymer complexes and multilayers were compared by variable temperature wide-line deuterium NMR spectroscopy Poly(methacrylic acid), deuterated at the methyl group, PMAA-d3, was complexed with five different hydrogen bond acceptor polymers—poly(ethylene oxide) (PEO), poly(acrylamide) (PAAM), poly(vinyl methyl ether) (PVME), poly(vinylpyrrolidone) (PVPon), and poly(vinylcaprolactam) (PVCL)—as well as with chitosan, where the interaction should be primarily ion pairing The overall chain mobility of PMAA in its water-saturated complexes was observed to increase in the following order: PVCL < PVPon < chitosan < PVME < PAAM < PEO For these polymer pairs, the same trend in chain mobility was also confirmed for the first few layers deposited on colloidal silica The observed chain dynamics correlate well with the reported variation of the critical pH, bilayer thickness, and the permeability for multilayer films of the same polymers In addition, the extent of 

Chain Dynamics of Water-Saturated Hydrogen-Bonded Polymer Complexes and Multilayers

Methyl esters of: 2-methyl [3-2H2]prop-2-enoic acid (methyl methacrylate-d2, CD2C(CH3)CO2CH3) and 2-[Me-2H3]methylprop-2-enoic acid (methyl methacrylate-d3, CH2C(CD3)CO2CH3) were prepared in high yield under mild conditions from carbomethoxymethyltriphenylphosphonium bromide in a new application of the Wittig reaction. The methyl ester of 2-methylprop[2H5]-2-enoic acid (methyl methacrylate-d5, CD2C(CD2CH3) was prepared from acetone-d6 via the acetone cyanohydrin method. Densities of all three monomers are reported at 25, 45 and 60°C.

The synthesis of deuterated methyl methacrylates

Use of radioisotopically labeled analytical reagents in organic chemistry

Gibberellin GA3 was prepared in low yield but at high specific activity (6.68 Ci/mmol) by platinum catalyzed exchange with tritiated water at 80°C for 16 hours.

Preparation of tritium-labelled gibberellin GA3 at high specific activity

Preparative, separative and analytical methods are described for the following labelled compounds: 4-amino[5-14C] formamidouracil (II), 1,3-dimethyl-4-amino[5-14C]formamidouracil (III), 1,3-dimethyl[S-14c]xanthine ([8-14C]theophylline) (IV), 1,3,7-trimethyl [8-14C]xanthine ([8-14C]caffeine) (V), 4-amino[2-14C]uracil (VI),′ 4-amino-5-nitroso[2-14C]uracil (VII), 4,5-diamino[2-14C]uracil (VIII), [2-14C]xanthine (IX), 3-methyl[2-14C]xanthine (X), [2-14C]theobromine (XI), [2-14c]theophylline (XII) and [2-14c]caffeine (XIII).

G. Ayrey

Papers

The synthesis of deuterated methyl methacrylates

Use of radioisotopically labeled analytical reagents in organic chemistry

Preparation of tritium-labelled gibberellin GA3 at high specific activity

Carbon‐14 ring labelling of some methylxanthines of pharmacological importance

Synthesis of vinyl [36cl] chloride